The present invention relates generally to zirconium oxide compositions. More specifically, the present invention relates to methods of making and using zirconium oxide compositions in crystalline form that have an effective sorption capacity, such as for phosphates.
In general, materials are known and used to remove constituents from fluids for a number of different applications including, for example, industrial, recreational, therapeutic, diagnostic and/or the like. For example, cationic polymers, anionic polymers and combinations thereof are typically used to purify a variety of different aqueous streams, such as industrial process streams, via ion exchange, flocculation or other suitable mechanism. Other materials are generally known as sorbent materials. The physiochemical properties of these types of materials enable them to remove suitable types of constituents from fluid via adsorption, absorbtion, chemisorption, chemical binding and/or other suitable mechanisms.
In general, materials are known in the art that are capable of removing phosphorous-containing constituents in solution. For example, zirconium oxide materials have been made by hydrolysis of a zirconium salt with a base. With these methods, the zirconium oxide is produced in a gel form. This can make it difficult to purify, such as by washing with water using a redispersion and decantation method.
Zirconium oxides, in general, have been made in crystalline or granular form. For example, particle formation is known to result from adding a low dielectric medium to an aqueous solution of zirconium salt. In this regard, monodispersed, submicron and nanoscale (e.g., <100 nm) zirconium oxide microspheres or powders have been synthesized under conditions that employ a 5:1 volume ratio of 2-propanol:water using hydroxypropyl cellulose and ammonia neutralization.
This synthetic method can be problematic. For example, the particle size of the zirconium oxide material is very fine in size, such as less than 100 nanometers (nm) as previously discussed. Further, the zirconium oxide displays a substantially low phosphate sorption capacity.
A need, therefore, exists to provide zirconium oxide compositions made from improved methods with sorption properties that can be effective even under physiological conditions and that can be readily and easily made at reduced costs, and easily adapted to existing systems, such as therapeutic systems.